How to check core temp of vacuum packed fresh & frozen seafood?

 We have recently started vacuum packing our seafood products.What would be the best way to check the product temperature (Core) of vacuum packs fresh & frozen? 

Regards

Hi CRix ,

Generally Frozen packed items are measured using a rapid-response sensor between the packs without movement by pressing two packs on the sensor between them and try to make it in way reducing the impact of outside air , for till the temperature reading is stable .

you can find a reference for that in FAO website ,the below link go to "Temperature measurement of frozen fish"  ^{_{look for the last paragraph}}

http://www.fao.org/wairdocs/tan/X5992E/X5992e01.htm

"The temperature of stacked packets may be measured by inserting a thin probe between packets, without disturbance, and allowing sufficient time for constant temperature to be reached. Provided a rapid-response sensor is used, the temperature of individually frozen fillets, or similar items, can be measured by pressing two fillets together with the sensor between them"

Best regards ,

Ehab

Frozen product temperature can be measured  by a couple of methods: 

- Destructive testing 

- Non- destructive testing. 

Detail of the same given below ( Reference: Codex Alimentarius-CODE OF PRACTICE FOR THE PROCESSING AND HANDLING OF QUICK FROZEN FOODS)

3.1.3 Non-destructive Temperature Measurement Non-destructive testing is rapid and can be done without unduly disturbing the load. However, because the outside temperature of the package or carton is being measured this may result in up to 2°C difference between the true product temperature and the reading obtained. Product surface temperature measurement undertaken non-destructively should: measure the temperature between cases on a pallet or between packages inside a carton; use sufficient pressure to give good thermal contact, and sufficient length of probe inserted to minimize conductivity errors; and use a probe with a flat surface to give good surface thermal contact, low thermal mass, and high thermal conductivity.

3.1.4 Destructive Temperature Measurement Temperature probes are not designed to penetrate quick frozen foods. Therefore it is necessary to make a hole in the product in which to insert the probe. The hole is made by using a pre-cooled sharp pointed metallic device such as an ice punch, hand drill or an auger. The diameter of the hole should provide a close fit to that of the probe. The depth to which the probe is inserted will depend on the type of product: where product dimensions allow, insert the probe to a minimum depth of 2.5 cm from the surface of the product. where this is not possible because of the size of the product, the probe should be inserted to a minimum depth from the surface of 3 or 4 times the diameter of the probe.

where it is not possible or practical to make a hole in certain foods because of their size or composition, e.g. diced vegetables, the internal temperature of the food package should be determined by insertion of a suitable sharp-stemmed probe to the centre of the package to measure the temperature in contact with the food. in order to measure the centre temperature in large products after the quick freezing process it may be necessary to insert the probe to a depth of more than 2.5 cm

Between pack "probes" are normally considered to be acceptable (or sometimes IR) but as previous people have said, surface temperature and core can be different.  It might be an idea to validate the differences and / or build them into your tolerances.